Spatial and Temporal Distribution of the Soil Carbon and Carbon Balance in Coastal Salt Pans
There are issues of soil salinization,inferiority,and low organic carbon content in coastal salt pans and those relevant studies are relatively lacking.This study aims to reveal the spatial and temporal distributions,influencing factors,and carbon cycling of the organic carbon in soils of coastal salt pans and land use types after the transformation.We select the soils from Xuwei New Area and Qingkou Salt Farm in Lianyungang,Jiangsu as the research objects.The soil samples were collected from the surface layer(0-20 cm,two phases of data in 2004 and 2019)and deep layer(150-200 cm,phase I data in 2004).The soil organic carbon(SOC),total carbon(TC),and total nitrogen(TN)were measured in the study.The results show that the SOC stock was increasing with the area of carbon sink area accounting for 69.4％and the area of carbon source area accounting for 30.6％.However,the SOC content and average carbon sequestration rate varied greatly among different site types.The SOC content was only distributed in the two grade intervals,low and medium in 2004,and medium in 2019,the SOC content was distributed in medium grade with the highest frequency.In the past 15 years,the SOC content was increased by 0.12％in salt pans 1(land type remained unchanged),0.42％in salt pans 2(cropland),and 0.13％in salt pans 3(construction land).The highest average carbon sequestration rate was found in the cropland type,with a value of 5.83 × 104 kg·km-2·a-1.The decomposition of soil organic car-bon in salt pans 1 was mainly caused through the heteroxic respiration pathway of microorganisms.Aerobic min-eralization of organic carbon is mainly achieved through aerobic mineralization by the fungi and bacteria.The anaerobic mineralization of organic carbon is mainly caused by SO42-reduction,so the rate of increase of the in-organic carbon is higher,reaching to 3.64 g·m2·a-1.The average SOC/TN value of the two phases of data in salt pans 1 is 9.9 positive,indicating a stable soil environment.The slight drop in SOC/TN in salt pans 3 is presumed to be caused by the decrease in the mineralization rate of SOC due to the increase of soil microbial load and enzyme activities.With the increasing environmental issues such as deteriorating soil quality,the re-sults of this study provide an important reference for the soil geochemical cycle in coastal salt pans and their land use types after the transformation.
organic carboninorganic carbonXuwei new areaQingkou salt farmcarbon cycle
国家科技期刊平台
NSTL
万方数据
维普
